JP2011024820A - Observation system for dental treatment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an observation system suitable for dental treatments and to reduce fatigue of a dentist during a treatment. <P>SOLUTION: An imaging apparatus 15 and a stereoscopic video display device 16 are supported by the supporting arm 12 of a stand device 1 via a first auxiliary arm 21 and a second auxiliary arm 22, respectively, so that each position can be moved largely as whole by the stand device 1 and the direction of the imaging apparatus 15 etc. can freely be changed by the first auxiliary arm 21 and the second auxiliary arm 22. Accordingly, the system is suitable for dental treatments and reduces the fatigue of the dentist during the treatment. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an observation system for dental treatment.

  2. Description of the Related Art When performing a surgical operation, a system is known in which an image is displayed on a display device that is supported separately from a camera while the surgical site is photographed with a camera. By separating the camera and the display device, the doctor can operate in an easy posture without looking into the eyepiece in an unreasonable posture, so that the doctor can be fatigued (for example, Patent Documents) 1).

US Patent Application Publication No. 2004/0036962

  However, although such a conventional observation system is suitable for a surgical operation, it cannot be applied to dental treatment as it is. That is, in the case of a surgical operation, it is not necessary to move the position of the camera greatly during the treatment, but in the case of a dental treatment, it is necessary to move the camera greatly each time because it is garbled several times during the treatment. In the case of surgery, it is not necessary to change the orientation of the camera frequently, but in the case of dental treatment, it is necessary to check the treatment site from all directions, so the orientation of the camera must be changed frequently. .

  The present invention has been made paying attention to such a conventional technique, and an object thereof is to provide an observation system suitable for dental treatment.

  According to the first aspect of the present invention, there is provided an imaging device capable of stereoscopically capturing a pair of left and right images having binocular parallax of a target portion via a first auxiliary arm at a distal end of a support arm extending in a lateral direction of the stand device 3D image display device capable of stereoscopically observing a pair of left and right electronic images displayed on a built-in display panel from a pair of eyepieces via a second auxiliary arm. It is characterized by being supported freely and freely.

  The invention described in claim 2 is characterized in that the image pickup apparatus has a single image pickup device, and a pair of left and right images are simultaneously picked up by the image pickup device.

  According to a third aspect of the present invention, the first auxiliary arm and the second auxiliary arm have a structure in which two parallel links are connected via a joint portion, and an imaging device and a stereoscopic image display device are rotatably attached to the tip. It is characterized by.

  The invention according to claim 4 is characterized in that a third auxiliary arm capable of supporting an instrument necessary for dental treatment is attached to the tip of a support arm extending in the lateral direction of the stand device.

  According to a fifth aspect of the present invention, there is provided a stand device in which a middle portion of the one vertical link in the parallel link mechanism formed by combining a pair of parallel vertical links and horizontal links is arranged on the upper portion of the base. A support arm is formed by extending the upper lateral link of the parallel link mechanism, and is supported at the pivot axis, and an imaging device and a stereoscopic image display device are provided at the lower end of the vertical tip link pivotally supported on the tip of the support arm. A horizontal axis point and a connection axis point which are supported on the first auxiliary arm and the second auxiliary arm and are located on the same horizontal line as the connection axis point at the connection axis point of the parallel link mechanism which is the starting point of the support arm A crank member having a vertical axis point located on the same vertical line as the vertical axis of the crank member, and the horizontal axis point of the crank member and a part of the main body are parallel to the vertical link of the parallel link mechanism and connected to the vertical link. A vertical sub link having the same length as the length from the axis point to the rotation axis point is connected, and the vertical axis point of the crank member and a part of the tip link are parallel to the support arm and the support arm. Connected by horizontal sub-links having the same length, and at the bottom of the parallel link mechanism, the rotation direction of the parallel link mechanism around the rotation axis and the rotation of the support arm around the connection axis It is a structure provided with a counterweight that cancels the weight applied in the direction.

  The invention according to claim 6 is characterized in that the tip of the support arm is bent downward.

According to the seventh aspect of the present invention, the first link element of the parallel link mechanism is pivotally supported by the stand main body, the counter weight is supported by one of the other mutually opposing link elements, and the other end is supported via the support arm. A link is pivotally supported, and a first sub-parallel link including the first link element and a second sub-parallel link including the support arm are configured such that each one link element is fixed in position to each other. In the torque transmission mechanism, the link element of the first sub-parallel link forming one end of the torque transmission mechanism is fixed to the stand body, and the link of the second sub-parallel link forming the other end of the torque transmission mechanism A stand device in which an element is fixed to the support arm to maintain a vertical state, and a pair of left and right images having binocular parallax of the target portion with respect to the tip arm are stereoscopically captured. A first auxiliary arm that movably supports a possible imaging device, wherein the position of the one link element is fixed to the third sub-parallel link in which one link element is fixed to the tip arm and the imaging device. A fourth sub-parallel link is connected by an angle changing means to form a torque transmission mechanism, and a pair of left and right electronic images displayed on a built-in display panel is paired with an eyepiece with respect to the tip arm. A second auxiliary arm that movably supports a stereoscopic image display device that can be stereoscopically observed from the first portion, wherein a first link element is fixed to the distal arm and a first sub-parallel link is fixed to the stereoscopic image device. And a sixth sub-parallel link to which the position of the link element is fixed is connected by an angle changing means to constitute a torque transmission mechanism.
According to the eighth aspect of the present invention, a clutch that fixes any adjacent link elements of the third sub-parallel link to each other, and an adjacent link element that fixes any of the fourth sub-parallel links are fixed to each other. And a clutch to be provided.

  According to the ninth aspect of the present invention, adjacent link elements of any of the fifth sub-parallel links are biased mutually, and adjacent link elements of any of the sixth sub-parallel links are biased mutually. It is characterized by being.

  According to the first aspect of the present invention, since the imaging device and the stereoscopic image display device are supported by the support arm of the stand device via the first auxiliary arm and the second auxiliary arm, respectively, the respective positions are entirely adjusted by the stand device. The first auxiliary arm and the second auxiliary arm can freely change the orientation of the imaging device and the like. Therefore, it is suitable for dental treatment, and fatigue during treatment by the dentist can be reduced.

  According to the second aspect of the present invention, since a pair of left and right images having binocular parallax are simultaneously imaged by a single image sensor, the color adjustment degrees of the left and right images are completely the same, and a clear stereoscopic image is obtained. Can be obtained.

  According to the third aspect of the present invention, the first auxiliary arm and the second auxiliary arm have a structure in which two parallel links are connected via the joint portion. It can be moved freely. In addition, since the imaging device and the stereoscopic image display device are rotatably supported at the tips of the first auxiliary arm and the second auxiliary arm, the orientation of the imaging device or the like can be freely changed at the moved position.

  According to the fourth aspect of the invention, since the third auxiliary arm is provided, an instrument necessary for dental treatment can be supported in addition to the imaging device and the stereoscopic image display device.

  According to the fifth aspect of the present invention, even if the support arm is rotated in the vertical direction or the entire parallel link mechanism is rotated in the horizontal direction, the distal end to which the first auxiliary arm and the second auxiliary arm are attached. The link is always kept vertical. Therefore, the imaging device and the stereoscopic video display device can be translated in the vertical direction and the horizontal direction while maintaining the posture and positional relationship between them, and observation by both is easy. In addition, since the vertical state of the front end link is always maintained, even if the state of the first auxiliary arm and the second auxiliary arm is changed and the distance from the front end link to the imaging device or the stereoscopic image display device is changed, the counter The overall balance state due to the weight is unchanged, and no further balance adjustment is required. That is, by maintaining the perpendicularity of the tip link, the balance state in the stand device does not collapse even if the position of the imaging device or the stereoscopic video display device changes.

  According to the invention described in claim 6, the tip of the support arm is bent downward, and the position of the support arm itself is avoided obliquely upward with respect to the first auxiliary arm and the second auxiliary arm attached to the tip. Therefore, even if the first auxiliary arm or the second auxiliary arm is moved, it is difficult to interfere with the support arm.

  According to the seventh aspect of the present invention, since the imaging device and the stereoscopic image display device are supported by the support arm of the stand device via the first auxiliary arm and the second auxiliary arm, respectively, the respective positions are entirely adjusted by the stand device. Can be moved greatly. Furthermore, since the inclination angle of the link side of the first auxiliary arm and the second auxiliary arm is fixed with respect to the stand body, the reference angle of the imaging device or the like as the load does not change, so that the orientation can be easily maintained. Or can be changed. Therefore, it is suitable for dental treatment, and fatigue during treatment by the dentist can be reduced.

  According to the invention described in claim 8, since the first auxiliary arm includes the third sub-parallel link and the fourth sub-parallel link, the first auxiliary arm can be easily and reliably fixed by the two clutches. it can.

  According to the ninth aspect of the invention, the fifth sub-parallel link and the sixth sub-parallel link of the second auxiliary arm are biased, so that the free deformation of the parallel link is limited and the second auxiliary arm can be easily made. Can be operated.

The whole side view which shows the observation system for dental treatment. The disassembled side view which shows the observation system for dental treatment. The side view which shows the imaging device and the three-dimensional video display apparatus which were supported by the front end link. The front view which shows the imaging device and the three-dimensional video display apparatus which were supported by the front end link. Explanatory drawing which shows the optical system of an imaging device. Sectional drawing which shows a three-dimensional video display apparatus. The figure which shows an example of the use condition of the observation system for dental treatment. The figure which shows the other example of the use condition of the observation system for dental treatment.

  1 to 8 are views showing a preferred embodiment of the present invention. In the following description, “front side” and “rear side” are based on the directionality shown in FIG.

  First, the stand device 1 will be described first. 2 is a base, and a caster 3 with a lock mechanism is provided on the lower surface of the base 2, and the floor 4 can be moved by the caster 3. A stand body 5 is installed on the base 2. The stand body 5 is supported so as to be rotatable in the horizontal direction with respect to the base 2. This rotation can be locked and freed by the electromagnetic clutch C1.

  A parallel link mechanism 6 is pivotally supported at a rotation axis b1 set on the front end side of the upper portion of the stand body 5. This parallel link mechanism 6 is formed by connecting both ends of a pair of parallel vertical links 7 and 8 and horizontal links 9 and 10 at connection axis points b2 to b5, respectively. The lower halfway portion of the front vertical link 7 is pivotally supported by the rotation axis b1. This rotation axis point b1 can also be locked and free in the rotation position in the longitudinal rotation direction S1 of the vertical link 7 by the electromagnetic clutch method. A counterweight 11 is attached to the rear end of the lower horizontal link 10.

  The upper side link 9 of the parallel link mechanism 6 is integrally formed with a support arm 12 that extends the side link 9 toward the front as it is, and its tip 12a is bent downward. A vertical tip link 13 is rotatably attached to a downward bent tip 12a at a connecting shaft point b6. Since the tip 12a is bent downward, the support arm 12 is inclined obliquely upward toward the front side. Regarding the weight balance of the load, the rotation axis b1 is a fulcrum and the connection axis b6 is an action point.

  A box-shaped support box 14 that is rotatable in the horizontal direction is provided below the tip link 13. The support box 14 supports the imaging device 15, the stereoscopic video display device 16, and the LED illumination 17. Support for the imaging device 15 and the like will be described later.

  Next, an L-shaped crank member 18 as an angle changing means is pivotally supported at the connecting shaft point b5 which is the starting point of the support arm 12, and the same horizontal line as the connecting shaft point b5 is supported on the crank member 18. A horizontal axis b7 located at H1 and a vertical axis b8 located on the same vertical line V as the coupling axis b5 are set.

  The horizontal axis point b7 and the connecting axis point b9 of the main body 5 located on the same horizontal line H2 as the rotation axis point b1 are parallel to the vertical link 7 and the vertical sublink 19 having the same length. It is connected.

  Further, between the other vertical axis b8 of the crank member 18 and the connecting axis b10 at the upper end of the tip link 13, it is parallel to the support arm 12 (correctly, a straight line connecting the connecting axis b5 to the connecting axis b6). In addition, the support arms 12 are connected by a horizontal sub link 20 having the same length as the length of the support arm 12 (the straight line length from the connection axis point b5 to the connection axis point b6). Accordingly, the link side b10-b6 to which the tip link 13 is fixed and the link side b1-b9 fixed to the stand body 5 are both ends of the torque transmission mechanism constituted by two connected parallel links and are always constant. The relative angle of Specifically, the link sides b10-b6 maintain a vertical state (vertical direction).

  Thus, by providing the vertical sublink 19, the crank member 18, and the horizontal sublink 20, the electromagnetic clutches of the stand device 1 are free, and the parallel link mechanism 6 is rotated forward and backward around the rotation axis point b1. The crank member 18 does not rotate even if the support arm 12 is rotated in the movement direction S1, the support arm 12 is rotated in the vertical rotation direction S2 around the connecting shaft b5, or they are simultaneously rotated. The vertical state of the tip link 13 is always maintained.

  The imaging device 15 is supported via the first auxiliary arm 21 and the stereoscopic image display device 16 is supported via the second auxiliary arm 22 with respect to the support box 14 of the tip link 13 maintained in this vertical state. The LED illumination 17 is supported via the third auxiliary arm 23. A handle h is also attached to the support box 14.

  The first auxiliary arm 21 and the second auxiliary arm 22 have a simple structure in which two parallel links 24 and 26 are connected via joint portions 25 and 27, and are expanded and contracted, whereby the imaging device 15 and the stereoscopic image display device 16 are expanded. Can be moved to a desired position.

  Each of the parallel links 24, 26 constitutes a first auxiliary arm 21 and a second auxiliary arm 22 as a torque transmission mechanism by combining two single parallel links via joint portions 25, 27. The joint portion 25 fixes the relative angles of the link sides of the first parallel link on the distal end link 13 side and the second parallel link on the imaging device 15 side. The joint portion 27 fixes the relative angles of the link sides of the first parallel link on the distal end link 13 side and the second parallel link on the stereoscopic image device 16 side. Accordingly, since one link side of the parallel links 24 and 26 is fixed to the tip link 13 that is always kept vertical, it is easy to maintain the posture even if the imaging device 15 and the stereoscopic video device 16 are moved. . Further, since the link sides fixed by the joint portions 25 and 27 as the angle changing means have a predetermined relative angle (right angle in the embodiment), torque can be effectively transmitted even when the load moves horizontally and vertically. Can do.

  The first auxiliary arm 21 is structured to hold the position by two electromagnetic clutches C2. That is, the first parallel link which is a torque transmission mechanism when two link sides connected to one of the four connecting shafts of the first parallel link on the tip link 13 side are fixed by the clutch C2. The whole is fixed. The clutch C2 only needs to fix adjacent link sides on any one connecting shaft. Further, when two link sides connected to one of the four rotation shafts of the second parallel link on the imaging device 15 side are fixed by the clutch C2, a second torque transmission mechanism is provided. The entire parallel link is fixed.

  The second auxiliary arm 22 is structured to hold the position by a reaction force and friction of a built-in spring (not shown). That is, similarly to the first auxiliary arm 21, each of the first parallel link on the distal end link 13 side and the second parallel link on the stereoscopic imaging device 16 side is configured by four link sides. When mutual frictional force is generated between adjacent link side elements and the tension of the built-in spring is applied, the free deformation of the parallel link is limited, and the structure of the parallel link and the position of the link side are fixed.

  The imaging device 15 and the stereoscopic image display device 16 are attached to the tips of the first auxiliary arm 21 and the second auxiliary arm 22 so as to be rotatable in the horizontal direction. The position of the rotation of the imaging device 15 in the horizontal direction is held by the electromagnetic clutch C3. The position of the imaging device 15 in the vertical direction is held by the electromagnetic clutch C4. The rotating state of the portion supported by the tip link 13 is shown by the arrow in the rotation direction in FIG. Further, the rotation axis of the electromagnetic clutch C3 is always maintained in the vertical state by the torque transmission mechanism from the link side b1-b9 to the link side b10-b6 and the first auxiliary arm 21, so that the imaging device 15 moves. Even the field of view does not tilt.

  The third auxiliary arm 23 has a structure that pivotally supports a plurality of arms, and can maintain the state by friction. A clamp 28 is provided at the tip, and an instrument such as the LED illumination 17 can be held.

  Next, the imaging device 15 will be described. The imaging device 15 includes an objective lens 29 and a zoom lens 30 inside. The light beam L guided from the treatment target T to the objective lens 29 at a predetermined convergence angle θ is transmitted through the objective lens 29 and then divided into two systems corresponding to the left and right eyes. After being passed, the optical element such as a prism (not shown) (for example, Japanese Patent No. 2607828) is guided to a single imaging device (CCD) 31 and can simultaneously shoot a right-eye image and a left-eye image. . The video imaged by the imaging device 15 can be observed by the stereoscopic video display device 16.

  The stereoscopic image display device 16 includes a pair of display panels (small LCDs) 33 inside a case 32, and displays a pair of electronic images having binocular parallax related to the target portion T imaged by the imaging device 15. Yes. A partition wall 34 for partitioning a space corresponding to the pair of display panels 33 is provided inside the case 32, and an electronic image displayed on each display panel 33 is converted to an eyepiece (loupe lens) of the corresponding eyepiece 35. By viewing with the pupil 37 of the dentist D through 36, the target portion T can be observed in three dimensions.

  All the weights of the imaging device 15, the stereoscopic image display device 16 and the like applied to the distal link 13 are balanced with the counterweight 11. Accordingly, the image pickup device 15 and the stereoscopic image display device 16 are moved by releasing the electromagnetic clutches of the stand device 1 and the image pickup device 15 is stopped in the air even if the hand is released at the destination (the balance is maintained). For). Accordingly, it is easy to move the imaging device 15 and the stereoscopic video display device 16 and the like.

  This balanced state is maintained even if the distance from the support box 14 to the imaging device 15 or the like is changed by bending the first auxiliary arm 21 and the second auxiliary arm 22 or the like. In other words, since the vertical state of the tip link 13 is always maintained, even if the imaging device 15 or the like approaches or separates from the tip link 13, the overall balance state by the counterweight 11 is unchanged, No balance adjustment is required. The torque related to the first auxiliary arm 21, the second auxiliary arm 22, and the tip link 13 is always compensated by the torque transmission mechanism from the link side b1-b9 to the link side b10-b6 already described.

  In addition, since the imaging device 15 and the stereoscopic video display device 16 are supported by the support box 14 below the tip link 13 that is maintained vertically, the imaging device 15 and the stereoscopic video display device 16 are positioned at their postures and positions. With the relationship maintained, the parallel link mechanism 6 and the support arm 12 can be rotated to translate in the vertical and horizontal directions.

  Therefore, it can respond even when the patient P is lying down as shown in FIG. 7, or can be handled even when the patient P is sitting down as shown in FIG. FIG. 8 shows an example in which the mirror 38 is held by the third auxiliary arm 23 instead of the LED illumination 17.

  Since both can be moved while maintaining the positional relationship between the imaging device 15 and the stereoscopic video display device 16, the imaging device 15 and the stereoscopic video display device 16 are once removed from the patient P, and then the imaging device 15 is again connected. When matched with the target portion T, the stereoscopic video display device 16 and the like can be reproduced at the original positions.

  Further, since the imaging device 15 and the stereoscopic video display device 16 can be moved independently by the first auxiliary arm 21 and the second auxiliary arm 22, respectively, even if one is moved, the other is not affected. Therefore, the dentist D can image the target portion T from any direction, and can observe the captured image at a free position by the stereoscopic image display device 16. Therefore, fatigue during treatment by dentist D can be reduced.

  Furthermore, even if the first auxiliary arm 21 and the second auxiliary arm 22 are freely moved, the tip 12a of the support arm 12 is bent downward, and the support arm 12 itself is relative to the first auxiliary arm 21 and the second auxiliary arm 22. Therefore, it is difficult to interfere with the first auxiliary arm 21 and the second auxiliary arm 22.

  In addition, since the video observed by the stereoscopic video display device 16 is captured by the single imaging element 31 of the imaging device 15, the pair of left and right electronic video displayed on the display panel 33 of the stereoscopic video display device 16 is color. Adjustments etc. are completely consistent, and clear stereoscopic observation can be performed. If the left and right images are picked up using the two left and right image sensors, the images sent from the two image sensors will be subtly shifted, and such shifted images will be observed for a long time. As a result, the visual fatigue of the dentist D is increased and a headache or the like may be complained. However, in this embodiment, since it images with the single image pick-up element 31, there is no such worry.

DESCRIPTION OF SYMBOLS 1 Stand apparatus 5 Stand main body 6 Parallel link mechanism 7, 8 Vertical link 9, 10 Horizontal link 11 Counter weight 12 Support arm 12a Tip 13 Tip link 15 Imaging device 16 3D image display device 17 LED illumination (instrument)
18 Crank Member 19 Vertical Sublink 20 Horizontal Sublink 21 First Auxiliary Arm 22 Second Auxiliary Arm 23 Third Auxiliary Arm 31 Imaging Element C1 to C4 Electromagnetic Clutch T Target Part D Dentist P Patient L Light Beam

Claims (9)

An imaging device capable of capturing a pair of left and right images having binocular parallax of the target unit in a three-dimensional manner is supported at the tip of a support arm extending in the lateral direction of the stand device in a movable and rotatable manner. And
A pair of left and right electronic images displayed on a built-in display panel is supported via a second auxiliary arm so that the stereoscopic image display device capable of stereoscopic observation from a pair of eyepieces is movable and rotatable. Observation system for dental treatment.   2. The dental treatment observation system according to claim 1, wherein the imaging apparatus has a single imaging device, and a pair of left and right images are simultaneously captured by the imaging device.   The first auxiliary arm and the second auxiliary arm have a structure in which two parallel links are connected via a joint portion, and an imaging device and a stereoscopic image display device are rotatably attached to the distal ends, respectively. The observation system for dental treatment according to claim 1 or 2.   The dental treatment according to any one of claims 1 to 3, wherein a third auxiliary arm capable of supporting an instrument necessary for dental treatment is attached to a tip of a support arm extending in a lateral direction of the stand device. For observation system. Stand device
The middle part of the one vertical link in the parallel link mechanism formed by combining a pair of parallel vertical links and horizontal links is supported by the pivot point of the stand body located at the upper part of the base,
The upper side link of the parallel link mechanism is extended to form a support arm, and an imaging device and a stereoscopic image display device are attached to the lower end of a vertical tip link pivotally supported on the tip of the support arm. Support through the arm,
A crank having a horizontal axis point located on the same horizontal line as the connection axis point and a vertical axis point located on the same vertical line as the connection axis point at the connection axis point of the parallel link mechanism serving as the starting point of the support arm Pivot the member,
A vertical sub-link having a horizontal axis point of the crank member and a part of the main body parallel to the vertical link of the parallel link mechanism and having the same length as the length from the connecting axis point to the rotating axis point of the vertical link. And connecting the vertical axis point of the crank member and a part of the tip link with a lateral sub-link that is parallel to the support arm and has the same length as the support arm,
The counter link weight is provided at the lower part of the parallel link mechanism so as to cancel the weight applied to the rotation direction of the parallel link mechanism around the rotation axis point and the rotation direction of the support arm around the connection axis point. The observation system for dental treatment according to any one of claims 1 to 4, wherein the observation system is for dental treatment.   6. The dental treatment observation system according to claim 5, wherein the tip of the support arm is bent downward. The first link element of the parallel link mechanism is pivotally supported by the stand main body, the counterweight is supported by one of the other mutually opposing link elements, and the tip link is pivotally supported by the other via the support arm,
In the torque transmission mechanism in which the first sub-parallel link including the first link element and the second sub-parallel link including the support arm are configured such that each one link element is fixed in position. The link element of the first sub-parallel link forming one end of the torque transmission mechanism is fixed to the stand body, and the link element of the second sub-parallel link forming the other end of the torque transmission mechanism is connected to the support arm. A stand device that is fixed in position and maintains a vertical state;
A first auxiliary arm that movably supports an imaging device capable of stereoscopically capturing a pair of left and right images having binocular parallax of the target portion with respect to the tip arm, wherein one link element is provided on the tip arm. A third sub-parallel link to be fixed and a fourth sub-parallel link to which the position of one link element is fixed to the imaging device are connected by an angle changing unit to constitute a torque transmission mechanism;
A second auxiliary arm that movably supports a stereoscopic image display device capable of stereoscopically observing a pair of left and right electronic images displayed on a built-in display panel from a pair of eyepieces with respect to the tip arm; A fifth sub-parallel link in which the position of one link element is fixed to the distal arm and a sixth sub-parallel link in which the position of one link element is fixed to the stereoscopic image device are connected by an angle changing means to generate torque. An observation system for dental treatment, comprising a transmission mechanism.   A clutch that fixes any adjacent link elements of the third sub-parallel link to each other, and a clutch that fixes any adjacent link elements of the fourth sub-parallel link to each other. The dental treatment observation system according to claim 7.   The adjacent link elements of any of the fifth sub-parallel links are biased with each other, and the adjacent link elements of any of the sixth sub-parallel links are biased with each other. Item 8. The dental treatment observation system according to Item 7.

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